Biophysics最新文献

The change in the structural characteristics of mitochondrial membranes isolated from epicotyls of Nemchinovsky 100 pea seedlings under the effect of sodium hydrosulfide at various concentrations has been studied. It was shown that seed treatment with sodium hydrosulfide solution at doses of 2 × 10^–4 M and 5 × 10^–6 M caused a shift of thermally induced structural transitions in mitochondrial membranes to lower temperatures and to an increase in the microviscosity of both lipid and protein regions of mitochondrial membranes with a decrease in their crystallinity. The presence of exogenous NaHS, as well as endogenous hydrogen sulfide, could increase the activity of antioxidant defense enzymes and caused the accumulation of osmolytes. As a result, the microviscosity of the lipid bilayer could increase. To test this hypothesis, the effect of the antioxidant resveratrol on the microviscosity of the mitochondrial lipid bilayer of epicotyles of pea seedlings was studied with both untreated and pretreated with NaHS seeds. The bioenergetic characteristics of mitochondria were also studied. Data have been obtained that confirm the effect of hydrogen sulfide on the structural characteristics of mitochondrial membranes by activating enzymes of antioxidant protection and accumulation of osmolytes.

The results of the analysis of time series for 5 years of observations of geophysical (ecological) rhythms, atmospheric pressure, and geomagnetic activity, were considered and their effect on human blood pressure and heart rate for time periods of fluctuations more than daily was assessed. It was found that during periods of about 15 days, when atmospheric pressure changed smoothly and slightly, a calmer heart rate and fluctuations in blood pressure were observed. Such “calm” periods of time were observed mainly in the summer months from July to August, usually only once per season. A comparison of the graphs of fluctuations in systolic pressure and the geomagnetic activity index showed a correlation between them three times higher than the correlation between systolic pressure and atmospheric pressure. This means that a geomagnetic field with an activity index of more than 2 had a greater effect on increasing systolic pressure in humans. The analysis also showed that the periods of peaks in the atmospheric pressure spectra were in good agreement with the periods of heart rate rhythms. The result indicates that these rhythms in humans might be affected by synoptic processes passing through the region in the atmosphere such as cyclones and anticyclones; ultimately, the well-being of elderly and sick people might depend on them. This study, as well as taking the variability of geophysical parameters published by hydrometeorological services into account, makes it possible to predict the state of human health.

The spatial distribution of GC content of fragments of the genomes of chloroplasts, mitochondria and bacteria was considered. It was found that the GC content of fragments of most genomes were distributed not chaotically, but in an orderly manner. Two principal types of distribution were found, gradient and centrally symmetric. Chloroplast genomes had only a gradient distribution. Bacteria had a centrally symmetric distribution for GC-poor genomes, and a gradient distribution for GC-rich ones. Both types of distributions occurred in mitochondria; the type of distribution depended on the type of organism.

Flash irradiation is an innovative method of therapy, which ensures that the therapeutic dose is brought to the pathological focus in times of the order of several tens of milliseconds. In this mode of irradiation, the degree of damage to normal tissues surrounding the tumor that fall under the influence of radiation decreases; at the same time, the effect on cancer cells remains at almost the same level, which improves the prospect of local control of the tumor with a lower frequency of side effects. The exact radiobiological mechanisms underlying the flash effect are not completely clear. This paper presents the results of work on the formation of a high-intensity proton beam with an energy of 660 MeV from the phasotron accelerator of the Joint Institute for Nuclear Research (Dubna), designed to conduct radiobiological studies of flash irradiation therapy on cell cultures and small laboratory animals (mice and rats). The survival rate of A549 cells under proton beam irradiation in flash and standard modes was compared. A difference was found in the change in the survival rate of A549 cells irradiated in flash and standard modes. The magnitude of the flash effect was represented by the dose change factor.

A method of nonequilibrium analysis of intramolecular oscillations of the amino acids glycine, phenylalanine, and tryptophan in an electric field of the terahertz and infrared ranges based on the calculation of amplitude-time realizations of the dipole moment and their Fourier frequency spectrum was implemented. Realizations lasting up to 2 ns were obtained by supercomputer modeling with a sampling step of 1 fs. The results showed the new possibilities of this method, which used an electric field modulated by a symmetrical meander for the first time. The fundamental concepts of the dynamic properties of biomolecules in external fields have been supplemented. The obtained data can be used in the development of nanobiotechnology, bioelectronic, and heterogeneous hybrid microelectronic devices with embedded biomolecular components.

Complete preservation of the antihypertensive activity of the freeze-dried drug Oxacom has been demonstrated after storing it for 15 years at room temperature in vessels with the air pumped out; this is due to the presence of a binuclear form of a dinitrosyl iron complex with glutathione in this drug. It was proposed that the oxidation of glutathione ligands in the composition of dinitrosyl iron complexes by air gradually penetrating into the vessels, which could lead to the decomposition of these complexes, was prevented by a significant amount of free (not included in dinitrosyl iron complexes) glutathione in this drug.

Using the Fenton reaction, a system has been modeled in which particles similar to those formed during the radiolysis of water were generated. The suppression of reactions caused by hydroxyl radicals formed in the system under the action of chlorophyllin is evaluated by the chemiluminescence method. It has been shown that sodium-copper chlorophyllin dose-dependently inhibits the chemiluminescence accompanying the phosphatidic acid peroxidation induced by the Fenton reaction. Based on this, it is concluded that copper chlorophyllin can inhibit the metabolism of lipid radiotoxins, lipid peroxidation (LP), caused by the attack of water radiolysis products on lipid molecules.

This study continues our previous research aimed at investigating changes in the pools of amino acids in the myocardium of the ground squirrel during winter torpor. Neurochemical profiles of amino acids and the secondary metabolites (taurine, phosphoserine, and cysteic acid) were explored in the neocortex of the ground squirrel at different stages of torpor: in the beginning of torpor (2–3 days) and during prolonged torpor (9–10 days), as well as during short-term winter arousal (winter activity, euthermia). Reduced excitatory neurotransmitter levels (glutamate by 7% and 14%; aspartate by 25% and 52% in a coordinated manner and the increased level of GABA, the main transmission inhibitor (by 50% and 67%) were observed from the onset of the torpor entry and at the end of the torpor arousal, respectively. Alanine, which was formed in negligible amounts in the neocortex in the summer season, increased at the initial stage of hibernation and after multiday torpor bout (by 98% and 126%, respectively), indicating a partial switch to anaerobic glycolysis. Short-term interbout euthermia returned levels of these substances back to normal. The behavior of glutamate and aspartate, the anaplerotic substrates, that supported cycling of the tricarboxylic acid cycle during torpor and winter activity periods was like their responses in the myocardium, though differed quantitatively. The responses of the neuromodulators such as glycine, threonine, and lysine differed radically when compared to their responses in the myocardium. No changes in taurine and phosphoserine pools were detected, but the level of cysteic acid decreased compared to the summer control from 0.51 ± 0.06 μmol/g to 0.07 ± 0.01 μmol/g at the end of torpor, while during winter euthermia it became 2 times lower than the summer level. Our data suggest that metabolic pathways involving anaplerotic amino acids of the neocortex are more active than the myocardium during winter torpor, while the pools of neuromodulators that regulate inhibition processes, increase.

It has been shown that nicotinamide coenzymes (NADPH, NADH, NADP⁺, and NAD⁺) are capable of generating superoxide anions (({text{O}}_{2}^{{ - ,bullet }})) in an alkaline environment. The superoxide-generating activity of the coenzymes is associated with high pH values and is sensitive to SOD. However, nicotinamide itself, being a functional part of coenzyme molecules, does not have this property. Polarographic studies showed that in the presence of coenzymes, molecular oxygen is consumed from the buffer, namely oxygen activation occurs due to the formation of ({text{O}}_{2}^{{ - ,bullet }}). Based on the obtained results and in accordance with the literature, our observations suggest that the formation of adducts of nicotinamide, which is part of the coenzyme molecule, and hydroxyl anions (OH^–) may lead to the formation of ({text{O}}_{2}^{{ - ,bullet }}). Under mild conditions in the organism, the studied coenzymes, while performing their main functions, are expected to generate superoxide, meaning that they can be signaling molecules.

The planarian nervous system is represented by a cephalic ganglion in the anterior part of the body and a pair of well-defined ventral nerve trunks extending along the entire body of the animal. The serotoninergic components of the nervous system are determined by the indirect immunocytochemical staining of the total preparations of the planarian Schmidtea mediterranea tissues, followed by analysis by fluorescent microscopy. The presence of serotoninergic components is found in the central and peripheral parts of the nervous system of the planarian S. mediterranea. The morphological parameters of serotonin-immunopositive structures are measured and the number of neurons in the cerebral ganglion is counted. The measurements are carried out on micrographs from stained total preparations obtained using a digital camera. The size of serotonin neurons in three areas of the body, the thickness of nerve trunks and cerebral ganglion, and the distance between nerve trunks and commissures are considered. For the first time, new quantitative data characterizing the morphological properties of the nervous system of the planarian S. mediterranea have been obtained. The regeneration of planarian eyes after decapitation and serotonin exposure is also studied. It is found that exogenous serotonin at a concentration of 0.01–1 μM accelerated eye differentiation during regeneration of the head end of S. mediterranea.